package nettyTest.netty3Test.proxy;

import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.Unpooled;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.channel.ChannelOption;

/**
 * @Auther     : yxpweb
 * @Date       : 2021/8/14 21:38
 * @Description: 创建连接真是服务器的代理客户端。并且收到消息直接转发给真实服务器
 */
public class HexDumpProxyFrontendHandler extends ChannelInboundHandlerAdapter {
	private final String remoteHost;
	private final int remotePort;

	// As we use inboundChannel.eventLoop() when building the Bootstrap this
	// does not need to be volatile as
	// the outboundChannel will use the same EventLoop (and therefore Thread) as
	// the inboundChannel.
	private Channel outboundChannel;

	public HexDumpProxyFrontendHandler(String remoteHost, int remotePort) {
		this.remoteHost = remoteHost;
		this.remotePort = remotePort;
	}

	@Override
	public void channelActive(ChannelHandlerContext ctx) {
		final Channel inboundChannel = ctx.channel();

		// Start the connection attempt.
		Bootstrap b = new Bootstrap();
		b.group(inboundChannel.eventLoop()).channel(ctx.channel().getClass()).handler(new HexDumpProxyBackendHandler(inboundChannel)).option(ChannelOption.AUTO_READ, false);
		ChannelFuture f = b.connect(remoteHost, remotePort);
		outboundChannel = f.channel();
		f.addListener(new ChannelFutureListener() {
			@Override
			public void operationComplete(ChannelFuture future) {
				if (future.isSuccess()) {
					// connection complete start to read first data
					inboundChannel.read();
				} else {
					// Close the connection if the connection attempt has
					// failed.
					inboundChannel.close();
				}
			}
		});
	}

	@Override
	public void channelRead(final ChannelHandlerContext ctx, Object msg) {
		if (outboundChannel.isActive()) {
			outboundChannel.writeAndFlush(msg).addListener(new ChannelFutureListener() {
				@Override
				public void operationComplete(ChannelFuture future) {
					if (future.isSuccess()) {
						// was able to flush out data, start to read the next
						// chunk
						ctx.channel().read();
					} else {
						future.channel().close();
					}
				}
			});
		}
	}

	@Override
	public void channelInactive(ChannelHandlerContext ctx) {
		if (outboundChannel != null) {
			closeOnFlush(outboundChannel);
		}
	}

	@Override
	public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
		cause.printStackTrace();
		closeOnFlush(ctx.channel());
	}

	/**
	 * Closes the specified channel after all queued write requests are flushed.
	 */
	static void closeOnFlush(Channel ch) {
		if (ch.isActive()) {
			ch.writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE);
		}
	}
}
